1. Field of the Invention
Embodiments of the invention generally relate to a cantilever system for a jack-up rig. In particular, embodiments of the invention relate to increasing the load-carrying capacity of a cantilever system that is used to support a platform on a jack-up rig.
2. Description of the Related Art
A jack-up rig is an offshore structure that generally includes a hull, a plurality of legs, and a lifting system that is configured to lower the legs into the seabed and elevate the hull to a position capable of withstanding various environmental loads, while providing a stable work deck. So that more wells can be drilled or worked over from the jack-up rig, cantilever systems have been integrated into the hull to extend and retract a drilling platform from the edge of the hull. The greater the distance that the cantilever system can safely extend the drilling platform from the hull, the greater the number of wells that can be drilled. Much effort has been expended in the reach of the cantilever system, while maintaining load requirements.
Normally, the cantilever system comprises a pair of I-beams located adjacent to each other, which support the drilling platform from underneath. The beams are longitudinally extendable from the hull to position the drilling platform out from the edge of the hull. The drilling platform itself and/or the drilling rotary system on the platform that is used to drill or work over a well are also movable in a transverse direction relative to the longitudinal axis of the beams to further increase the area within which a well can be drilled.
The cantilever system must be capable of supporting the weight of the drilling platform and the equipment supported by the platform. As the drilling platform is extended further from the edge of the hull, the loads on the cantilever system increase. To increase the capacity of the cantilever system, the beams can be formed from a stronger material and/or the beam structure can be increased so that the beams are larger and heavier. However, stronger materials can significantly add to the cost of the cantilever system, and increasing the size and weight of the cantilever system requires substantial modifications to the hull and legs of the rig that are needed to support the cantilever system.
Therefore, there is a need for a new and improved cantilever system and method of use.